Instruments that record seismic wave amplitude at a given point on the Earth’s surface.
Instrument that measures vertical ground movement.
vertical ground movement
Extremely hard rock mass joined with the subsoil.
Horizontal support that is secured to the ground.
Very solid vertical support.
Independent of ground movement, it remains stationary during an earthquake, thus serving as a reference for measuring the amplitude of tremors.
It keeps the mass from moving.
Writing instrument that converts ground movement into a line.
Secured to the ground, it rotates under the pen, recording ground movements on paper.
Graphic representation produced by a seismograph; the stronger the tremors, the greater the oscillations on the paper.